Revealing the role of atomic arrangement on the thermal transport properties of Janus WSSe

Janus Transition metal dichalcogenides (TMDs) are a representative class of two-dimensional materials and are regarded as promising candidates for electronic and optical applications. As one of the key physical properties of two-dimensional materials, their thermal transport properties have been extensively investigated. However, a recent study suggests that Janus TMDs may stabilize a previously overlooked ground state with a distinct atomic arrangement (npj Computational Materials, 10 (2024) 232). Consequently, thermal conductivity reported by earlier works may lead to potential inaccuracies. Therefore, clarifying whether atomic arrangement affects their thermal transport properties and revealing the role of atomic arrangement on the thermal transport properties is essential for their practical applications. In this work, we take WSSe as a representative system and systematically investigate the thermal transport properties of the newly identified S-III Janus structure and perform a direct comparison with the conventional S-I phase. We found that the thermal conductivity is mainly contributed by acoustic phonon branches in both S-I and S-III structures. The atomic arrangement can weaken scattering rate of both longitudinal and transverse acoustic branch and leads to a longer phonon lifetime and thermal conductivity.